a. Field of the Invention
The present invention relates to a hand-held pump apparatus, notably to a peristaltic pump for use in sterile or clean-room environments, and to a pump head for use in the pump apparatus.
b. Related Art
A peristaltic pump is a positive displacement pump used to dispense a fluid from a container through a flexible dispensing tube. Hand-held peristaltic pumps are typically used to pump various fluids, such as a clean or sterile fluid, where there is a need for the pump not to contaminate the fluid, or to pump aggressive fluids such as adhesives, so that the fluid cannot contaminate the pump. A peristaltic pump allows delivery of a specified volume of fluid for a given actuation movement independently of the viscosity of the fluid.
US 2010/0313996 describes a hand-held peristaltic pump apparatus for dispensing fluid from a rigid container. The apparatus includes a hand-operated peristaltic pump. The pump supports a rigid container which includes a fluid to be dispensed. A separate dispensing tube as well as a vent tube extends from the container through the pump.
The peristaltic pump is actuated by a user grasping the pump head in one hand, and using one or more fingers to depress a trigger which operates a rotary member that bears against the dispensing tube and the vent tube. Operation of the pump causes fluid to be pumped out from the container through the dispensing tube and air is pumped into the container through the vent tube so as to equalise pressure in the container.
A problem with the use of hand-held peristaltic pumps in sterile or clean-room environments is that not all of a user's fingers typically rest on the trigger. A user's finger which is not on the trigger is liable to trapped between the trigger and an adjacent surface of the pump head. This can cause damage to a glove worn by the user and contamination of the sterile or clean environment. Prolonged use may also promote repetitive strain injury (RSI).
Where it is necessary for the liquid in the container to be sterilised by irradiation by gamma or other rays, this causes heating of the liquid up to about 55° C. and creates an internal pressure. Such pressure is not released by a vent tube which passes through the pump head because, like the dispensing tube, the vent tube is sealed by pressure of the peristaltic rotary member. In this case, the vent tube may instead be open to atmosphere via a one-way valve such as a duck-bill valve, although such a vent/valve arrangement does not allow air to be pumped into the container to replace liquid which is pumped out. Use of a collapsible container instead of a rigid container allows the internal pressure to be adjusted by reduction in the internal volume of the container as liquid is pumped out. However, it is desirable to reduce the complexity of the pump.